<template>
    <div class="home-page">

  <div class="banner">
    <div class="container">
      <h1 class="logo-font">conduit</h1>
      <p>A place to share your knowledge.</p>
    </div>
  </div>

  <div class="container page">
    <div class="row">

      <div class="col-md-9">
        <div class="feed-toggle">
          <ul class="nav nav-pills outline-active">
            <li class="nav-item" v-if="user">
              <nuxt-link 
                exact
                class="nav-link"
                :class="{
                  active: tab === 'your_feed'
                }"
                :to="{
                  name: 'home',
                  query: {
                    tab: 'your_feed'
                  }
                }"
                >Your Feed</nuxt-link>
            </li>
            <li class="nav-item">
              <nuxt-link class="nav-link" 
                exact 
                :class="{
                  active: tab === 'Global Feed'
                }" 
                :to="{
                  name: 'home'
                }">Global Feed</nuxt-link>
            </li>

             <li class="nav-item" v-if="tag">
              <nuxt-link class="nav-link"  
                exact
                :class="{
                  active: tab === 'tag'
                }" 
                :to="{
                  name: 'home',
                  query: {
                    tab: 'tag',
                    tag: tag
                  }
                }"># {{ tag }}</nuxt-link>
            </li>
          </ul>
        </div>

        <div class="article-preview" v-for="article in articles" :key="article.slug">
          <div class="article-meta">
            <nuxt-link :to="{name:'profile',
            params: {
              username: article.author.username
            }}"><img :src="article.author.image" /></nuxt-link>
            <div class="info">
              <nuxt-link :to="{name:'profile',
            params: {
              username: article.author.username
            }}" class="author">{{ article.author.username }}</nuxt-link>
              <span class="date">{{ article.createdAt | date("MMM DD,YYYY") }}</span>
            </div>
            <button 
              :disabled="article.favoriteDisabled"
              @click="onFavorite(article)"
              class="btn btn-outline-primary btn-sm pull-xs-right" 
              :class="{
              active: article.favorited
              }"
            >
              <i class="ion-heart"></i> {{ article.favoritesCount }}
            </button>
          </div>
          <nuxt-link class="preview-link"
          :to="{
            name:'article',
            params: {
              slug: article.slug
            }
          }"
          >
            <h1>{{ article.title }}</h1>
            <p>{{ article.description }}</p>
            <span>Read more...</span>
          </nuxt-link>
        </div>

        <!-- 分页列表    -->

        <nav>
          <ul class="pagination">
            <li class="page-item" 
            v-for="item in totalPage" 
            :key="item" 
            :class="{
              active: item === page
            }">
              <nuxt-link 
              class="page-link" 
              :to="{
                name: 'home',
                query: {
                  page: item,
                  tag: $route.query.tag,
                  tab: tab
                }
              }">{{ item }}</nuxt-link>
            </li>
          </ul>
        </nav>
      </div>

      <div class="col-md-3">
        <div class="sidebar">
          <p>Popular Tags</p>

          <div class="tag-list">
            <nuxt-link 
              :to="{
                name:'home',
                query: {
                  tag: tag,
                  tab: 'tag'
                }
              }"
             class="tag-pill tag-default"  v-for="tag in tags" :key="tag">{{ tag }}</nuxt-link>
          </div>
        </div>
      </div>



    </div>
  </div>

</div>
</template>

<script>

import { getArticles, getFeedArticles, addFavorite, deleteFavorite } from '@/api/article'
import { getTags } from '@/api/tag'

import { mapState } from 'vuex'
export default {
    name:'home',
    async asyncData ({ query }) {
      // 得到页码和查询参数
      const page = Number.parseInt(query.page || 1)
      const limit = 20;
      const tab = query.tab
      const tag = query.tag
      const loadArticles = tab === "your_feed" ? getFeedArticles : getArticles

      const [articleRes, tagRes] = await Promise.all([
        loadArticles({
          limit: limit,
          offset: (page - 1) * limit,
          tag: tag
        }),
        getTags()
      ]) 
      const { articles, articlesCount } = articleRes.data

      articles.forEach( article => {
        article.favoriteDisabled = false
      })

      const { tags } = tagRes.data

      return {
        articles: articles, // 文章列表
        count: articlesCount, // 文章总数 
        limit: limit, // 每页大小
        page: page, // 页码
        tags: tags, // 标签列表
        tab: tab, // 选项卡
        tag: tag // 标签
      }
    },
    computed: {
      ...mapState(['user']),
      totalPage() {
        return Math.ceil(this.count / this.limit)
      }
    },
    watchQuery: ['page', 'tag', 'tab'],
    methods: {
      async onFavorite (article) {
        article.favoriteDisabled = true
        if (article.favorited) {
          // 取消点赞
         
          await deleteFavorite(article.slug)
          article.favorited = false
          article.favoritesCount -= 1
        } else {
          // 添加点赞
          await addFavorite(article.slug)
         
          article.favorited = true
          article.favoritesCount += 1
        }
         article.favoriteDisabled = false
      }
    }
};
</script>

<style scoped lang="less">

</style>
